1. Field of the Invention
The present invention relates to a flyer frame, and more particularly, to a device for stopping a bobbin rail of the flyer frame at a desired position after a full bobbin state is obtained.
2. Description of the Related Art
Known in the prior art is an automatic bobbin conveyor system used in a spinning factory, wherein conveyor lines connected between flyer frames and spinning frames are provided at the ceiling of the factory, for carrying bobbin carriages suspending full bobbins along the conveyor lines from the flyer frames, and delivering the same to auxiliary rails of creels of the respective spinning frames. Almost empty bobbins at the creel stands of the respective spinning frames are then replaced by the full bobbins at the auxiliary rails, and an ending process is carried out for introducing an end of a roving of a full bobbin into a trumpet of the spinning frame. The roving remaining on the almost empty bobbin is then removed, to thereby obtain an empty bobbin which is then returned to the flyer frame for repeated use thereof.
In such a system, a mechanism is employed for obtaining an automatic ending operation upon a replacement of the bobbins at the spinning frames. Such an automatic ending mechanism is provided with a suction nozzle for engaging the free end of the roving of a full bobbin, to draw out a predetermined length of the roving therefrom by unwinding same, and the suction nozzle holding the end of the roving is then moved to a trumpet of a draft roller unit of a spinning frame, for introducing the roving end into the trumpet to thereby carry out an ending operation. (See, for example, Japanese Unexamined Patent Publication No. 62-53425 and Japanese Unexamined Patent Publication No. 64-52828.) To obtain a desired ending operation by such an automatic ending mechanism, a free end of a roving of a full bobbin is located and held at a predetermined fixed height from the bottom end thereof, to thus bring the free end of the roving to a position facing the inlet opening of the nozzle of the automatic ending mechanism.
As is well known, a full bobbin state at the flyer frame is detected by a sensor for detecting when a predetermined length of the roving is wound on a bobbin. In the prior art, to obtain the predetermined location of the free end of the roving of a bobbin, so as to facilitate the ending operation at the spinning frame, the flyer frame continues to operate even after the detection of the full bobbin state, until the bobbin rail holding the bobbins reaches a predetermined vertical position corresponding to the desired vertical location of the free end of the roving of the bobbin, without changing the speed of the vertical reciprocation movement of the bobbin rail.
Note, the predetermined constant vertical position of the bobbin rail when a predetermined length of the roving is wound on a bobbin is, in general, not always obtained because errors inevitably occur in the parameters determining the length of the roving wound on the bobbin such as, for example, a tension of the roving, while winding same. Furthermore, when the full bobbin condition is obtained, the bobbin rail is usually stopped when moved upward, to thereby prevent a switching of the bobbin rail when the bobbin rail is moved downward to carry out a doffing operation. Where a full bobbin condition is obtained just after the bobbin rail has passed the above-mentioned predetermined position, during the upward movement of the bobbin rail, the bobbin rail must be stopped at the predetermined position after the completion of almost one complete upward and downward movement, while the spinning is continued. This causes an excessive amount of the roving of two winding layers having a length of as much as 70 to 80 yards to be wound, as the average value of the count thereof after the predetermined length of the roving on the bobbin is obtained, which is the maximum value of the error in length generated in full bobbins to be doffed.